Update README.md erlang version requirement
Update README.md erlang version requirement

https://github.com/evanmiller/ChicagoBoss/issues/247
ChicagoBoss/ChicagoBoss,aherranz/ChicagoBoss,aherranz/ChicagoBoss,yunkai/ChicagoBoss,solatis/ChicagoBoss,frkarl/ChicagoBoss,powermedia/ChicagoBoss,lamptt/ChicagoBoss,7i11/ChicagoBoss,7i11/ChicagoBoss,lamptt/ChicagoBoss,danikp/ChicagoBoss,uselessd/ChicagoBoss,yunkai/ChicagoBoss,uselessd/ChicagoBoss,danikp/ChicagoBoss,frkarl/ChicagoBoss,solatis/ChicagoBoss,synlay/ChicagoBoss,synlay/ChicagoBoss,powermedia/ChicagoBoss,ChicagoBoss/ChicagoBoss